Gone back around midnight twice... for a drink (3,3)
I believe the answer is:
egg nog
'a drink' is the definition.
(I've seen this before)
'gone back around midnight twice' is the wordplay.
'midnight twice' can mean two substitutions for 'midnight'.
'back' says the letters should be written in reverse.
'around' is an insertion indicator.
'midnight' becomes 'g' (the middle letter in 'night').
'midnight' becomes 'g' (the middle letter in 'night').
'gone' reversed gives 'enog'.
'g'+'g'='gg'
'enog' going around 'gg' is 'EGG-NOG'.
'for' acts as a link.
(Another definition for egg nog that I've seen is " alcoholic drink".)